1. Field of Invention
This invention relates to a novel Halbach array electric motor with substantially contiguous electromagnetic cores, which is applied to an in-wheel electric motor as one sample implementation thereof.
Generally the goal of implementing Halbach arrays in electric motors is to maximize efficiency, increase power or to reduce size and weight by harnessing the Halbach effect; otherwise an ordinary unenhanced motor would suffice. A stack of coated thin sheets of high-silicon electrical steel that comprise the vertical and horizontal cores have a magnetic resistance that is a thousand times less than empty air. This means that relying upon empty air to transmit magnetic flux is massively inefficient compared to using a magnetically permeable core.
While permanent magnets are pure polar cores, electromagnets are in sharp contrast, generally comprised of a magnetically permeable metal core and a magnetic coil. Because of the specific orientation required to enable the Halbach array effect, electromagnets cannot merely be arranged like permanent magnets with the expectation of successfully creating a strong Halbach array effect, since the magnetic coils prevent physical contact between the electromagnet's vertical and horizontal cores.
It is important to stress that magnetic coils are made of copper, different in composition and intended function to the laminations of high-silicon electrical steel that comprise the core. Moreover the copper is energized. The magnetic flux from the horizontal cores of the Halbach array will be blocked by the energized copper enveloping the vertical cores. And since copper is not the same as the non-energized, magnetically absorbent high-silicon electrical steel of the core, a significant amount of the magnetic flux from the horizontal core will end up dispersed and misdirected. Essentially, a motor or generator with electromagnets merely arranged as a Halbach array but without substantial contiguity (i.e. physical contact) between horizontal and vertical cores will have a severely diminished or even a completely disabled Halbach array effect. As a consequence, the motor will be massively inefficient and likely worse in performance when compared to an ordinary motor of the same dimensions.
As pointed out earlier, a core-less Halbach array comprised only of coils, while marginally lighter, would be a thousand times less efficient, consuming more power to achieve the same output as a motor with a magnetically permeable metal core, and is thus completely counter to the original reasons for implementing a Halbach array configuration in a motor or generator.
All of these foregoing problems and challenges have been resolved in the present invention.
2. Description of Prior Art
There are known numerous prior art devices which allege to be Halbach array motors, but are fundamentally different from the present invention due to the following reasons: a) only permanent magnet Halbach arrays are used on the rotor and ordinary, non-Halbach electromagnets are used as the stator, b) the electromagnets used are merely arranged to approximate a Halbach array sequence, but does not provide any means to provide substantial contiguity between its electromagnetic cores, which severely decreases or even completely negates the Halbach array effect, and c) only permanent magnet Halbach arrays are used, in combination with an external, ordinary electromagnet motor.
U.S. Pat. No. 8,513,849 including U.S. Pat. Nos. 8,183,731 and 7,352,096 are almost identical, and discloses a generator where permanent magnets are mounted on discs but spaced so far apart for a Halbach array in the supplied drawings that it is unlikely to provide a strong Halbach array effect. Likewise the electromagnets used are clearly non-Halbach, and neither do they show a means to provide substantial contiguity between cores. These three patents are thus completely different from the present invention. Interestingly, none of the drawings in these patents depict a valid Halbach array sequence.
U.S. Pat. Nos. 6,906,446 and 6,858,962 are almost identical, and discloses generator featuring a permanent magnet Halbach array on the stator, but the rotor is non-Halbach, and is thus different from the present invention.
U.S. Pat. No. 7,598,646 discloses a bicycle wheel equipped with a Halbach array, where the motive force for the bicycle wheel are two external arches comprised of electromagnets that are merely arranged in Halbach Array formation, on either side. The provided drawings clearly show that the electromagnets used have no means to provide substantial contiguity between cores, which are isolated by the energized magnetic coils. This will severely diminish or even negate the Halbach array effect, and is thus fundamentally different from the present invention.
U.S. Pat. No. 7,541,813 for cylindrical Halbach sequenced electromagnets used as a resistivity tool in oil drilling and is thus fundamentally different from the present invention.
U.S. Pat. No. 5,705,902 for a generator with octagonal induction bars but implemented as an ironless or coreless system, and is thus fundamentally different from the present invention.
U.S. Pat. No. 6,841,910 discloses a magnetic coupling for pumps that uses a Halbach array that is driven by an external drive motor, it is thus very different from the present invention.
U.S. Pat. No. 8,009,001 discloses a means of concentrating Halbach Arrays to create a ‘hyper’ Halbach using permanent magnet arrays. This is purely about arranging permanent magnets and fundamentally different from the present invention.
U.S. Pat. Nos. 7,540,004 and 7,031,116 discloses a Halbach array used as part of an actuator or coil on a magnetic head for hard disks, and is thus fundamentally different from the present invention.
Launchpoint Technologies developed a closed electric hub motor for unmanned aerial vehicles (UAVs) that uses two backing plates equipped with permanent magnets in Halbach array sequence sandwiching a non-Halbach array stator that has three phase Litz wire winding. It is thus very different from the present invention.
Protean Electric's™ In-Wheel Electric Drive discloses a fully-integrated in-wheel electric hub motor completely separate from the tire and alloy wheel. It does not make use of any Halbach arrays in its configuration. It is thus very different from the present invention.
Michelin™ ActiveWheels discloses an in-wheel implementation that derives propulsion from one small electric motor at one corner of the wheel, and the suspension system is integrated into the wheel's hub. This implementation is a gear-driven wheel powered by a micro motor. This implementation does not does not disclose a Halbach array configuration and is thus different from the present invention.